Field of the Invention
The present invention relates to a method of transferring a thin film, a method of manufacturing a thin film transistor, a method of forming a pixel electrode of a liquid crystal display device.
Background
An oxide semiconductor film is a material having both visible light transparency and electrical conductivity, and therefore has been used as a transparent electrode of a flat panel display (FPD), a thin film solar cell, or the like.
On the other hand, an oxide semiconductor film has semiconductor properties and therefore is used also as a semiconductor layer of a thin film transistor. The oxide semiconductor film is generally deposited by a vacuum deposition method such as a sputtering method. Since the vacuum deposition method requires a large-scale vacuum apparatus, the manufacturing cost increases.
As a further simple deposition method of the oxide semiconductor film, wet deposition methods such as a sol-gel method, an electroless deposition method, and an electrolytic deposition method are known. However, although in the deposition methods, growth (deposition) is performed at high temperatures by heating a substrate or the like, and thereby an oxide semiconductor film having a high crystalline quality can be obtained, it is difficult to obtain an oxide semiconductor film having a high crystalline quality at low temperatures (about 100 to 200° C.) which a resin substrate represented by polyethylene terephthalate (PET) or the like is able to withstand.
Examples of a method of obtaining an oxide semiconductor film having a high crystalline quality such as one obtained by a vacuum deposition method at low temperatures and at normal pressures include a transfer method. For example, Japanese Patent Application, Publication No. H8-160424 discloses a technique of using a transfer foil obtained by sequentially forming at least a transparent conductive layer and an adhesion layer directly or via a release layer on a plastic film and transferring the transparent conductive layer to a substrate.